Method of producing pneumatic tubes for vehicle tires and the like



f 1,638,659 Aug-9 1927- w. l.. FAIRCHILD METHOD OF PRGDUCING PNEUMATIC TUBES FOR VEHICLE TIRES AND THE LIKE Filed Sept. ll, 1924 INVENTOR Mu TEA l4 FA/RcH/D l ATTORNEY 'nevertheless be manufactured more cheaply Patented Aug. 9, 1927.-

STATES M338, orales.

WALTER L. FAIRCHILD, 0F NEW-YORK, N. Y.

METHOD 0F IPRODUCING PNEUMATIC TUBES FOR VEHICLE TIRES ND THE' LIKE.

Application led September 11, 1924. Serial No. 737,088.

This invention relates to a new and improved inner tube for pneumatic tires and the like, and also to a new and lmproved method of roducing the same.

One of t e objects of the invention is to provide a pneumatic tube with an improved method of securing the valve stem in position upon the tube, wherein danger of leakage in the associatedv parts is practically eliminated.

Another object ofthe invention is to provide a new and improved method of uniting the ends of the tubular structure, and at the same time securing the mounting of the valve stem in position within the tube.

Another object of the invention is to provide a new and improved method of attaching Athe valve stem to the tube whereby it is more securely fastened to, or anchored in the wall of the tube than it has been possible to secure this result -in methods heretofore practiced, and also whereby there is less likehood of a leak occurring in or .about the point of anchorage of the valve stem in the wall of the tube.

A further object of the invention is to provide a tube of the above character which, while more efficient than tubes of this character as heretofore constructed, can

than can such tubes as heretofore constructed.

A further object of the invention is to provide atube of the above character, which is without a re-vulcanized splice, and which so far as appearance and operation is concerned, is of seamless construction.

Other objects and aims of the vinvention more or less specific than those referred to above, will be in part obvious and in part pointed out in the course of the following description of the steps and the relation of each step to one or more ,of the others thereof employed in carrying out my rocess, and the scope of protection. Contemp ated will be indicated in the appended claims.

In the accompanying drawings, wherein I have illustrated a preferred form of embodiment of my invention: l

Figure 1 is a longitudinal, sectional view of an inner tube produced in accordance with my improved method.

Figure 2 is a cross sectional view taken substantially on the line 2-2 of Figure 1, looking in the direction of the arrows.

Figure 3 is a plan view of a blank from which is formed a reinforcing ring employed in the manufacture of my improved tube; and l Figure 4 is a transverse cross-sectional view taken on the line 4-4 of Figure 3.

Referring now to the drawings, wherein similar reference characters refer to similar parts throughout'the several views thereof, the reference lillustrates my improved pneumatic tube, having a free end portion 2 and a free end portion 3, which end portions, when the tube is completed, lie in abutting relation along the line 4, at which point, as will be hereinafter described, these end portions are formed into substantially a homo'- geneous structure.

,At this point it may be noted that the material of the tube atthe time the ends thereof are positioned in abutting relation, when the valve stem is inserted through the tube, and the reinforcing parts for the valve .stem positioned therein, is preferably composed of raw rubber, that is to say, rubber in the same condition as it was when it was discharged from the tube forming apparatus.

In the present embodiment of my invention I prefer to form this tube as a straight tubular member, preferably by means of what is known as a tubing machine the rubber when discharged from said tubing machine containing the proper ingredients commonly employed in rubber com ounds for tubes, so that when the vulcanlzation process is effected upon the tube, thel material thereof is reduced to its finished state. Therefore, for the urposes of this description, it will be un erstood that the tube 1, which is not shown in its entirety, has been produced in the manner next above described.

Referring now to Figures 2, 3 and 4, the reference numeral 5 denotes a blank for a reinforcing ring 6 (Figure 2). The blank 5 is composed of two strips 6 and 7 of raw or unvulcanized rubber, containin sub stantially the same ingredients as t e unvulcanized tube itself. These strips are preferablyshaped by a cutt-in device to the form shown in Figure 3, so t at when theyv are superimposed one upon another their edges will lie in exact registry. They arepreferably provided with widened substantially elliptically formed intermediate por preferably provide a piece of canvas 9, the

Same being substantially of elliptical form, as shown in Figure 3, said canvas being `frictioned upon b`oth sides with unvulcanized rubber.

Having provided these parts, the friction canvas piece 9 is interposed between the raw rubber blanks 6 and 7. The blankv thus formed is subjected to pressure which may be applied in any suitable manner, as by means of presser rolls, whereby the portions of said blanks in contact with the friction strip are firmly united thereto by cohesion, and the portions of the blanks 6 and 7 where they comein direct contact with each other, are formed into a substantially homogeneous mass.

The blank 5 is then provided with the central aperture 10, whereupon the valve stem 11 is inserted so that the neck 12 of the valve Stem will lie in engagement with the edges of the aperture 10, and the head 13 will lie in contact with the material of the blank 5 surrounding the aperture 10.

Having performed these operations, the ends 14 and 15 of the blank 5 are brought together and slightly overlapped, whereupon pressure is exerted to these overlapped portions, whereby a substantially homogeneous union is eeoted between them, 'said blank, by this operation, being formed into a ring 6', having an external circumference substantially equal to the interior circumference of the tube, as shown in Figure 2 of the drawings.

The valve'stem 11 is then inserted through an aperture 16 formed in the end 2 of the tube 1, and at the same time the ring 6 is partially inserted iii'said end of the tube so that one end of the ring projects outwardly from said end of the4 tube, as shown in Figure Lof the drawings. The material of the tube andthe ring, Vand all that part of the structure surrounding the neck 12 of the valve stem, are then thoroughly worked and 'kneaded so that all contacting surfaces of the raw rubber will be homogeneously united and the surrounding edges of the tube as Well as of the reinforcing ring, and the neck of the valve stem, caused closely to lie in contact with each other.

The next operation is to bring around the free end 3 of the tube 1, and project it over the projecting end 17 of the ring 6, in such a way that the ends 2 and 3 of the tube will lie in abutting relation about the `ring 6. The free end 8 thus positioned labout the ring 6', and said ring 6 are again thoroughly worked and kneaded so that all the enga ing parts of the ,raw rubber structure wi 'l be thoroughly united by cohesion to form a substantially homogeneous structure.

At this point it may be noted that I contemplate so kneading or working the abutting ends of the raw rubber tube, the parts surface of the reinforcing ring with the ends of the tube, that a substantially homogene- -ous unit will be established between all the rubber engaging parts, and the rubber material and canvas strip caused Iclosely to hug the neck of the valve stem before any further steps of my improved method are carried on. The tube thus formed is now ready for the vulcanization operation.

In vulcanizing my improved tube, the same is preferably positioned in an individual in old, suitably heated as by means of a steam jacket or otherwise. The apparatus utilized inperforming this operation may be substantially the same as that shown in my United States Patent Reissue N o. 16,542, dated February 8, 1927. Prior or subsequent to the placing of the tube in the vulcanizing mold, however, the valve stem is connected with a vacuum apparatus which exhausts all the conned air from the tube and collapses the same. The tube, when enclosed in the mold, is then expanded by steam, or 'other vulcanizing gas passed thereinto through the Valve stem, means being provided to control the temperature as well as the pressure of the steam or other vulcanizing gas projected into the tube. The vulcanization operation is then carried on in a manner which is well understood.

At the end of the vulcanization process the steam or gas pressure is relieved, and if desired, the valve stem of the tube may heA connected with a vacuum apparatus to free the walls of the tube from th'e mold. After the vulcanization process has been carried on, as above described, the tube is removed from the mold, and the spreader member 18 is positioned upon the valve stem in theusual manner, and locked thereupon as by the clamp nut 19.

It will accordingly be seen that I have provided a pneumatic tube and the new and improved method of producing the same, wherein all possibility of air leakage between the walll of the tube and the valve stem parts is eliminated. I have also provided a structure wherein the anchorage of the valve stem to the wall of the tube is such that there is no dan er of the valve stem being torn from or oosened from its anchorage therein during extreme service conditions, by reason of the fact that the tube itself and the anchorage of the Valve stem are simultaneously subjected to the vulcanization process, all parts of the homogeneous structure will be equally vulcanized, no parts thereof being subjected to a second vulcanization operation, as is usual in inner tubes as heretofore constructed.

It will be understood thatvarious changes may be resorted to in the form, construction and arrangement of the several parts and in the material employed and steps followed,

without departing from the spirit and scope of m invention; hence, I do not. intend to be iimited to the details herein shown and described except as they may be included in the claims.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is: l

l. A method of producing a pneumatic tube for vehicle tires,I which comprises providing a tube of unvulcanized rubber, providing a ring composed of two superimposed strips of unvulcanized rubber with interposed fabric reinforcing means, inserting a valve stem through said ring, positionin said rin into one of the free ends of sai tube so t at said valve stem extends therethrough, abutting the opposite end of said tube with the first mentioned end thereof, so that both ends of the tube embrace said ring, kneading the material of said tubes adjacent the ends thereof so that the free ends of said tube and said rin become substantially homogeneous, and t en vulcanizing said tube and ring.

2. A method of producing a pneumatic tube for vehicle'tires, which comprises; providing a tube of unvulcanized rubber, providing a rin composed of unvulcanized rubber and fa ric and havin a transversely elongated intermediate portion, inserting a valve stem through said ring, positionln said ring into one of the free ends of sai ltube so that said valve stem extends therethrough, abutting the opposite end of said -tube with the first mentioned end thereof,

so that both ends of the tube embrace said ring, and then vulcanizing said tube and' rlnlg.

n testimony whereof, I aiix my signature. y

`WALTER L. FAIRCHILD. 

